Vehicle fuel tank

ABSTRACT

The inside wall of a fuel tank, and a sub-component are provided with locking means in the form of complementary formations that allow the sub-component to be coupled to the inside surface of the fuel tank wall. Interlocking of the complementary formations is achieved by moving the sub-component towards the wall providing angular movement to the sub-component relative to the fuel tank.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit from U.S. provisional application No.61/332,113 filed May 6, 2010 which is incorporated herein by referencein its entirety.

FIELD

This invention relates generally to fuel tanks for vehicles.

INTRODUCTION

Vehicle fuel systems must be leak tight under all conditions, and mustensure that the fuel received is moved safely through the fuel fillerpipe to the fuel tank, and that the vapour generated during the fillingprocess is moved to an appropriate onboard vapour storage container.Typically, fuel tanks will have various parts attached to the fuel tankshell in order to satisfy these requirements.

Fuel tanks are primarily made from either metal or plastic. The wall ofa plastic fuel tank may comprise one or multiple layers, which may bedesigned with barrier properties to enhance the plastic fuel tank'sability to keep volatile organic compounds inside the tank.

An example of a part commonly attached to plastic vehicle fuel tanks isa gas vent valve, typically used to permit air to flow into the fueltank as fuel is consumed from (and exits) the tank, and to furtherpermit fuel vapour to flow from the fuel tank as fuel is loaded therein,during normal operation of the vehicle. In order to prevent fuelspillage when a vehicle is tipped or rolled, gas vent valves can beconfigured to close in response to a change in the orientation of thefuel tank.

A part is most commonly attached to a fuel tank shell by either welding,or mechanically attaching the part to the fuel tank. Example attachmentmethodologies advanced to date include those described in U.S. Pat. Nos.5,083,583; 6,058,963; 6,584,996; 7,059,305; 7,228,847; 7,290,675; and,7,455,190; and in U.S. Publication Nos. 2002/0020705 and 2006/0260129.

Conventionally, attaching a part to a fuel tank requires that a hole becut into the tank body where the part is to be attached, which cansignificantly diminish the fuel tank barrier properties. An object ofthe present invention is to provide a means for attaching a part to theinside of a fuel tank without compromising the integrity of the tankwall.

SUMMARY

In one broad aspect, there is provided a fuel tank having a wall with aninside surface defining the interior of the tank, and locking meanscoupling a fuel tank sub-component to said inside surface of the wallwithout compromising the integrity of the wall, said locking meanscomprising complimentary male and female formations on saidsub-component and said inside surface respectively, said formationsbeing shaped to permit engagement of the formation on the sub-componentwith the formation on the wall by movement of the sub-component towardsthe wall and subsequent interlocking of said formations by angularmovement of the sub-component with respect to the wall in a firstdirection.

The sub-component may be a valve or other part having a housing providedwith locking formation(s), or the formation(s) may be on a separatehousing that receives the part.

The part for mounting in the interior of the fuel tank may be, forexample, a gas vent valve, a control valve, a fuel limit vent valve,baffles, a line retaining clip, or an internal retention clip. Thehousing of/for the part may have a vapour exit port and may be injectionmolded from a resilient material. In one embodiment, the material may bea plastic material selected from the group of: polyoxymethylene andpolyphthalamide.

In one embodiment, the male formation is on the sub-component and maycomprise a plurality of locking elements and a plurality of retentionwings. Further, the female formation is on the inside surface of thefuel tank and may comprise a plurality of angled ramps for slidingengagement with the plurality of locking elements, a plurality oflocking recesses for accepting the plurality of locking elements whenthe sub-component is coupled to the inside surface of the wall, and aplurality of undercut portions for engagement with the plurality ofretention wings when the sub-component is coupled to the inside surfaceof the wall. More specifically, the plurality of angled ramps maycomprise two diametrically opposed angled ramps.

In another embodiment, the fuel tank may further comprise alignmentmeans aligning the sub-component within the fuel tank, said alignmentmeans comprising a second set of complimentary male and femaleformations on the sub-component and the inside surface respectively,said second formations being shaped to permit alignment of thesub-component within the fuel tank prior to coupling.

The fuel tank may be manufactured by a method selected from the groupof: stamping, hydro forming, blow molding, injection molding, and twinsheet vacuum forming.

In another broad aspect, there is provided a sub-component for couplingto an inside surface of a wall of a fuel tank without compromising theintegrity of the wall, said sub-component comprising a formation shapedto engage with a complementary formation on the wall of the fuel tank bymovement of the sub-component towards the wall and subsequentinterlocking of said formations by angular movement of the sub-componentwith respect to the wall, said formations comprising male and femaleformations, respectively.

The sub-component may be a valve or other part having a housing providedwith locking formation(s), or the formation(s) may be on a separatehousing that receives the part.

The housing may be injection molded. In one embodiment, the housing maybe a plastic material selected from the group of: polyoxymethylene andpolyphthalamide. Further, the plastic material must be resistant tofuel.

The part for mounting in the interior of the fuel tank may be a gas ventvalve, a control valve, a fuel limit vent valve, baffles, a lineretaining clip, or an internal retention clip. The housing may have avapour exit port and may be injection molded from a resilient material.In one embodiment, the material may be a plastic material selected fromthe group of: polyoxymethylene and polyphthalamide.

In one embodiment, the male formation is on the sub-component and maycomprise a plurality of locking elements and a plurality of retentionwings.

DRAWINGS

In order that the invention may be more clearly understood, referencewill now be made to the accompanying drawings which illustrate aparticular preferred embodiment of the invention by way of example, andin which:

FIG. 1 is a perspective view of the inside of a fuel tank, the fuel tankhaving a sub-component coupled to an inside surface thereof;

FIG. 2 is a perspective view of the sub-component of FIG. 1;

FIG. 3 is a side view of the sub-component of FIG. 1;

FIG. 4 is a bottom view of the inside of the fuel tank of FIG. 1; and,

FIGS. 5, 6 and 7 are diagrammatic sequential views illustrating movementof the sub-component to a fully locked position within the fuel tank.

DESCRIPTION OF VARIOUS EMBODIMENTS

Referring first to FIG. 1, a fuel tank designed for securing a fuel tanksub-component therein without compromising the integrity of the fueltank wall is shown by way of example and is generally designated byreference numeral 100. Part of the fuel tank 100 has been cut away inorder to show the interior thereof. A sub-component secured within thefuel tank 100 is shown in FIG. 1 by way of example and is generallydesignated by reference numeral 200. The sub-component 200 is attachedto the inside wall 104 of the fuel tank 100 manually or using anautomated process whereby an extended robot arm enters the fuel tank 100through an opening to perform the attachment.

The fuel tank 100 is made of plastic, as is the sub-component 200, andthe sub-component 200 is configured to house a valve (not shown). Thesub-component 200 is coupled to the fuel tank 100 without compromisingthe surrounding inside surface 125 of the fuel tank 100 by providing afemale formation on the inside surface 125 of the fuel tank 100 designedto engage with a complementary male formation provided on thesub-component 200. Throughout the description, reference may be made tocomplementary formations (or complementary design features) “on the fueltank”, or “provided on the fuel tank”. Such references shall beunderstood to mean “on the inside surface of the fuel tank”, or“provided on the inside surface of the fuel tank”, respectively.

Referring now to FIG. 2, the sub-component 200 of FIG. 1 is shown inperspective view, in the absence of the fuel tank 100. As mentionedabove, a male formation is provided to the sub-component 200 forengagement with a complementary female formation provided on the insidesurface 125 of the fuel tank 100 (FIG. 1). The male formation compriseslocking elements 210 and retention wings 220. The illustrated embodimentcomprises two locking elements 210 and two retention wings 220 andfunctions similarly to a bayonet-style fitting (employing a twist tolock technique to secure the sub-component to the interior of the fueltank). A person of ordinary skill in the art will appreciate that thesub-component 200 may be designed with a different number of lockingelements 210 and retention wings 220.

Each locking element 210 is designed for engagement with a complementaryrecess (or pocket) of the inside wall 104 of the fuel tank 100 (FIG. 1).In the illustrated embodiment, the locking elements 210 aresubstantially cylindrical in shape and have a rounded contact portion215 (i.e. a substantially hemispherical end portion). The contactportion 215 of the locking element 210 is the portion thereof (typicallythe end portion) configured for engagement with the complementary recess(or pocket) of the fuel tank 100 when coupling the sub-component 200 tothe fuel tank 100 (FIG. 1). Those ordinarily skilled in the art willappreciate that the shape of the locking elements 210 may vary providedthat the contact portions 215 are designed complementary to lockingrecesses formed in the fuel tank 100, which will be described furtherbelow. As will also be discussed further below, when the sub-component200 is coupled to the inside wall 104 of the fuel tank 100, the contactportions 215 of the locking elements 210 engage with locking recesses onthe fuel tank 100 (FIG. 1) to prevent rotation of the sub-component 200about a central axis 230 thereof, and to restrict the sub-component's200 mobility in the upward direction (indicated by the arrow labeled U).

The male formation provided to the sub-component 200 also comprisesretention wings 220. In the illustrated embodiment, the sub-component200 has two retention wings 220 substantially diametrically opposed. Asmentioned above, the number of retention wings 220 provided to thesub-component 200 may be more or less than two. Further, it will beappreciated that where two retention wings 220 are used, they need notbe substantially diametrically opposed. As will be discussed furtherbelow, when the sub-component 200 is coupled to the fuel tank 100 (FIG.1), the retention wings 220 frictionally engage with complementaryundercuts provided in the fuel tank 100 to restrict the sub-component's200 mobility in the downward direction (indicated by the arrow labeledD).

The male formation provided to the sub-component 200 includes optionalassembly fingers 255 in association with the retention wings 220. Eachwing normally (but not necessarily) will be provided with an assemblyfinger. As discussed further below when the sub-component 200 is coupledto the fuel tank 100 (FIG. 1), the assembly fingers 255 are the first toengage the complementary undercuts provided in the fuel tank 100 and ineffect guide the retention wings 200 to frictionally engage thecomplimentary undercut provided by the fuel tank 100.

Additionally, the sub-component 200 comprises an additional (or second)male formation shaped to permit alignment of the sub-component 200within the fuel tank 100 when engaged with an additional (or second)female formation provided in the fuel tank 100 (FIG. 1). In theillustrated embodiment, the additional male formation of thesub-component 200 comprises the male locating element 240 protrudingfrom the centre of the sub-component 200. The male locating element 240is provided with a pivot surface 245, which when pressed against acomplementary female formation in the fuel tank 100, indicates theproper positioning of the sub-component 200 for subsequent coupling tothe fuel tank 100 (FIG. 1).

As seen in FIG. 3, the pivot surface 245 is planar and protrudes higherthan the rest of the male locating element 240. Accordingly, the pivotsurface 245 may provide the first point (or surface) of contact betweenthe sub-component 200 and the fuel tank 100 when the latter is offeredto the former for coupling. Further, the top surface of the malelocating element 240 is beveled from the outer periphery of the pivotsurface 245 to the outer periphery of the male locating element 240. Aswill be discussed further below, a complementary bevel is providedaround a central locating surface of the fuel tank 100 (FIG. 1) tofacilitate proper alignment of the sub-component 200 within the fueltank 100 prior to, and during coupling.

With returning reference to FIG. 1, the sub-component 200 illustratedhas an opening 250 for receiving a valve or other part (not shown) thatis required to be attached inside a fuel tank 100. Examples of partsthat may be required to be attached inside a fuel tank 100 include, butare not limited to, valves (e.g. gas vent valves, control valves, andfuel limit vent valves), baffles, line retaining clips, and internalretention clips. The sub-component 200 illustrated is exemplary only. Itis designed for use with a separate gas vent valve (not shown) and has avapour exit port 252 to allow fuel vapour to flow from the valve (notshown) to a desired location, e.g. an onboard vapour storage container(not shown), through a hollow vapour flow tube 254 of the sub-component200. The area around opening 250 may be provided with a range offastening means, such as mechanical, welds, adhesive, press-fit, rivetsor screws. Within the opening may be threads, such as for holding a fuelsystem component in place. Seals may be provided, particularly where oneof the alternate non-threaded fastening means are used.

Referring to FIG. 2, the sub-component 200 illustrated has two metaldisks 256 installed one on the top of each of the diametrically opposedlocking elements 210 and inside the rounded contact portion 215. A thirdmetal disk is inserted into the pivot surface 245 on the male locatingelement 240. These disks allow for subsequent confirmation that thesub-component 200 is in the correct and final locked position during theassembly process.

Exemplary technologies for confirming correct location include metaldetection, x-ray, and industrial imaging technology. In general, thetechnology used to locate the metal disks would verify proper locationhaving regard to visual features (registration points) on the exteriorsurface of the tank, which may be either purposely placed registrationpoints, or visual features that are already part of the tank itself.

As noted previously, instead of being a multiple-piece assembly (as inthe illustrated embodiment), the sub-component 200 may be unitarywherein the locking formation(s) are integrally formed on the valve orother part itself. For example, the male formations of the sub-component200, as described above, may be integrally formed on a housing of thevalve.

As will be discussed in further detail below, an appropriate amount ofresiliency is required of the sub-component 200. This resiliency may beachieved by injection-molding the sub-component 200 from certain plasticmaterials. The sub-component 200 must also be fuel resistant. In apreferred embodiment, the sub-component 200 may comprise eitherpolyoxymethylene or polyphthalamide plastic with fuel-resistantproperties.

Reference is now made to FIG. 4, in which a female formation of theinside wall 104 of the fuel tank 100 is illustrated by means of a bottomview of the cut away fuel tank 100 of FIG. 1, in the absence ofsub-component 200. The female formation of the fuel tank 100 iscomplementary to the male formation of the sub-component 200 asdescribed above, and may comprise angled ramps 110, locking recesses112, and undercut portions 120.

In the embodiment illustrated, two locking recesses 112 are formed inthe inside wall 104 of the fuel tank 100, as are the angled ramps 110for sliding engagement with the locking elements 210 of thesub-component 200 (FIG. 2). The ramps 110 slope inward (i.e. towards theinterior of the fuel tank 100) in the direction of the arrows, i.e. froma distal end 114 of the ramp 110 (furthest from the correspondinglocking recess 112) towards the proximal end 116 of the ramp 110(adjacent to the corresponding locking recess 112). In a preferredembodiment, the profile of each angled ramp 110 largely conforms to theprofile of the contact portion 215 of the complementary locking element210 of the sub-component 200, thereby facilitating sliding of thelocking elements 210 along the angled ramps 110 in the direction of thearrows in FIG. 4. It will be appreciated that a different number ofangled ramps 110 may be formed in the fuel tank 100 should asub-component 200 with a different number of locking elements 210 beprovided.

A locking recess 112 is formed in the inside wall 104 of the fuel tank100 adjacent the proximal end 116 of each angled ramp 110. The lockingrecesses 112 are essentially hemispherical seats for receiving thelocking elements 210 of the sub-component 200. The orientation of thelocking recesses 112 relative to each other corresponds to theorientation of the locking elements 210 of the sub-component 200relative to each other. For example, where the locking elements 210 ofthe sub-component 200 are diametrically opposed, the complementarylocking recesses 112 in the fuel tank 100 will also be diametricallyopposed. It will be appreciated that, as was the case with the number ofangled ramps 110, more or less than two locking recesses 112 may beformed in the fuel tank 100 depending on the number of locking elements210 provided on the sub-component 200. It will also be appreciated thatthe locking recesses 112 need not be hemispherical in shape; rather,they need only complement the shape of the locking elements 210 of thesub-component 200.

In the illustrated embodiment, the formation on the inside wall 104 ofthe fuel tank 100 further comprises undercut portions 120. As shown inFIG. 1, the undercut portions 120 may be formed by appropriately shapingthe wall 104 of the fuel tank 100. The undercuts are appropriatelyoriented and spaced from the other components of the formation on thefuel tank 100 so as to be frictionally engaged first by the assemblyfingers 255 and then the retention wings 220 of the sub-component 200when the sub-component is coupled to the fuel tank 100. As apparent fromFIG. 1, when the sub-component 200 is coupled to the fuel tank 100, theundercuts restrict the sub-component's 200 mobility by restricting itsmovement towards the center of the fuel tank 100.

With continuing reference to FIG. 4, an optional second female formationon the inside wall 104 of the fuel tank 100 is described. The secondfemale formation provides alignment means for the sub-component 200within the fuel tank 100 and comprises a central locating surface 145for engagement with the complementary pivot surface of the sub-component200 when the sub-component 200 is offered to the inside wall 104 of thefuel tank 100 prior to coupling. In a preferred embodiment, the centrallocating surface 145 of the fuel tank 100 conforms largely with thepivot surface 245 of the sub-component 200. For example, where the pivotsurface 245 is planar (as in the embodiment of FIG. 3), the centrallocating surface of the fuel tank 100 is also planar. It will beappreciated by those skilled in the art that the central locatingsurface 145 and the pivot surface 245 are not required to be planar. Forexample, in some embodiments, the central locating surface and pivotsurface may be conical in configuration. In the illustrated embodiment,the second female formation in the fuel tank 100 also comprises abeveled surface 148, largely conforming to the beveled top surface ofthe male locating element 240 between the periphery of the pivot surface245 and the periphery of the top surface of the male locating element240.

The female formations described above in connection with the insidesurface wall 104 of the fuel tank 100 may be provided by blow moldingthe fuel tank 100 using an appropriately configured mold. Alternatively,the fuel tank 100 can be manufactured with the appropriate formationsthrough stamping and hydro forming processes (for metal fuel tanks), andinjection molding and twin sheet vacuum forming processes (for plasticfuel tanks).

Installation of the sub-component 200 within the fuel tank 100 is nowdescribed with reference to FIGS. 1, 2, and 4 to 7. The sub-component200 is offered to the inside the wall 104 of the fuel tank 100 proximatethe female formations provided therein (i.e. the sub-component 200 ismoved towards the wall 104). Proper alignment of the sub-component 200within the fuel tank 100 is achieved by pressing the pivot surface 245of the sub-component 200 against the central locating surface 145 on thefuel tank 100. In the embodiment illustrated, the locking elements 210are aligned with the distal ends 114 of the angled ramps 110 such thatthe retention wings 220 do not interfere with the undercuts 120.Pressure towards the wall 104 is applied to a portion of thesub-component 200 (typically a central portion), and the sub-component200 is rotated (i.e. provided an angular movement) with respect to thefirst wall 104 to interlock the formation on the sub-component 200 withthe formation on the fuel tank 100.

The sub-component 200 is turned in the direction indicated by the arrowsin FIG. 4 such that the locking elements 210 slide up the angled ramps110. By maintaining the applied pressure throughout the rotation of thesub-component 200, the angled ramps 110 increasingly displace thelocking elements 210, causing the sub-component 200 to flex at theattachment regions 260 (FIG. 1) of the locking elements 210. Once thesub-component 200 is rotated such that the locking elements 210 reachthe locking recesses 112, energy stored in the resilient material of thesub-component 200 causes the attachment members 260 to return to theirnatural (un-flexed) position and the locking elements 210 to snap intothe locked position within the locking recesses 112. Once thesub-component 200 has reached this position, the retention wings 220 areengaged with the undercuts 120 and the sub-component 200 is effectivelycoupled to the wall 104 of the fuel tank 100, thereby immobilizing thesub-component 200 within the fuel tank 100 without compromising theintegrity of the wall 104.

FIGS. 5, 6 and 7 are diagrammatic illustrations showing the sequence ofmovement of one of the locking element 210 into the correspondinglocking recess 112. In FIG. 5, the retention wings 220 are shown priorto entering the corresponding undercuts 120 formed in the tank. In FIG.6, the retention wings are within the respective undercuts and fullyflexed at the attachment regions 260. In FIG. 7, the locking element 210is seated within the associated recess 112 and the attachment regions260 of the retention wings have partially relaxed.

It will of course be appreciated that the preceding description relatesto a particular preferred embodiment of the invention and that manymodifications are possible, some of which have been indicated above, andothers of which will be apparent to a person skilled in the art. Forexample, the male and female formations of the fuel tank andsub-component may be interchanged (i.e. a male formation may be providedto the fuel tank and a complementary female formation may be provided tothe sub-component).

Male locating element 240 may be a separately-formed piece thatassembles on the main body portion comprising the retaining wings. Forexample, the male locating element 240 may be positioned in an openingof the main body portion, and is locked into place when the assembly isfitted to the corresponding female formations on the tank. While thesub-component is generally regarded as being a plastic component, othermaterials may be used including magnesium alloys (thixomolding), othermetals such as aluminum using a die cast forming process andthermosetting materials.

Finally, it is to be noted that a plurality of sub-components may beused to attach a single part to a tank—for example, baffles may requiremultiple contact points within a tank.

The invention claimed is:
 1. A fuel tank having a wall with an insidesurface defining the interior of the tank and a fuel tank sub-componentadapted to be coupled to said inside surface of the wall at a locationin which the wall is free of openings that pass through the wall andwithout compromising the integrity of the wall; the fuel tank comprisinga plurality of spaced apart locking recesses formed in the wall of thefuel tank and a plurality of angled ramps, the ramps extending between adistal end spaced from an adjacent one of the locking recesses and aproximal end terminating at the adjacent one of the locking recesses,wherein each of the ramps slopes inwardly towards the interior of thefuel tank from the distal end to the proximal end; the fuel tank furthercomprising a plurality of undercut portions formed in the wall of thefuel tank, wherein the undercut portions are spaced between the lockingrecesses; the subcomponent comprising a central male locating elementdefining a central axis, a plurality of spaced apart locking elementsconnected to the locating element by attachment regions projectingradially from the locating element, and a plurality of retention wingsextending radially from the locating element and spaced between adjacentlocking elements; wherein the locking elements engage and slide alongthe angled ramps and are matingly received by the locking recesses andthe retention wings are lockingly engaged with the undercut portions inresponse to rotation of the sub-component with respect to the wall ofthe fuel tank in a first direction to thereby interlock thesub-component to the fuel tank.
 2. The fuel tank of claim 1, wherein thesub-component comprises a housing having an opening receiving a part formounting in the interior of the fuel tank.
 3. The fuel tank of claim 2,wherein the part is a valve.
 4. The fuel tank of claim 3, wherein thevalve is one of a gas vent valve, a control valve, and a fuel limit ventvalve.
 5. The fuel tank of claim 2, wherein the housing is injectionmolded.
 6. The fuel tank of claim 2, wherein the housing comprises aplastic material selected from the group of: polyoxymethylene andpolyphthalamide.
 7. The fuel tank of claim 1, wherein the fuel tankfurther includes a central locating surface recessed in the wall of thefuel tank for receiving the male locating element of the sub-componentto align the sub-component with the fuel tank along the central axis. 8.The fuel tank of claim 7, wherein the plurality of angled rampscomprises two diametrically opposed angled ramps.
 9. The fuel tank ofclaim 1, wherein the fuel tank is manufactured by a method selected fromthe group of: stamping, hydro forming, blow molding, injection molding,and twin sheet vacuum forming.
 10. The fuel tank of claim 7, whereineach retention wing is provided with an assembly finger extendingcircumferentially from the retention wing for engaging and guiding saidretention wings into said undercut portions of said fuel tank inresponse to rotation of the sub-component relative to the fuel tank inthe first direction.
 11. A fuel tank as claimed in claim 1, wherein thesub-component is provided with at least one metal element that isdetectable from externally of the fuel tank to confirm full engagementof the component with the fuel tank.